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The authors have realised an InGaAs/GaAs vertical cavity surface emitting laser grown on a GaAs (311)B substrate by metal-organic chemical-vapour deposition. A carbon auto-doping technique was used to avoid the difficulty of p-type doping (>1019 cm–3) AlAs for a distributed Bragg reflector. A low electrical resistance of p-type GaAs/AlAs DBRs on GaAs (311)B was obtained by using delta doping and compositional grading layers. The lowest threshold was 16 mA at room temperature CW operation for a 50 µm diameter device. The threshold current density is 810 A/cm2 which is reasonably low for non-optimised experimental conditions. The polarisation state was stable.

An InGaAs/GaAs quantum well laser using p-type δ-doping selectively in the barriers has been demonstrated to reduce the threshold current and carrier lifetime. A δ-doping technique is proposed, based on the experimental evidence of high density carbon inclusion during AlAs growth by metal organic chemical vapour deposition (MOCVD). A threshold current density as low as 160 A/cm2, (54 A/cm2/well) has been obtained for three quantum well stripe lasers grown at 1.7 × 1018 cm–3 carbon doping.